Why does SERVER_PORT not always get passed to my appserver?

Question

I have an nginx set up in a very boring fashion as a reverse proxy to an appserver. But sometimes my upstream gets the environment variable SERVER_PORT, sometimes it does not. Anyone suggest why it's not consistent or how I might troubleshoot it?

upstream starman {
   server unix:/var/run/starman.sock;
}

server {
<snip>
location / {
  proxy_pass        http://starman;
  proxy_set_header  SERVER_PORT $server_port;
}

Answer 1

It may be other location in your config, passing requests without adding SERVER_PORT.